Plato views the genesis of the Spartan constitution in a quite innovating way. Before him (Herodotus, Xenophon), it was attributed to Lycurgus alone ; according to him, it was truly an history. At the beginning was the kingship, which soon became double by twin birth ; then two other divine interventions successively created the Gerousia (through the action of Lycurgus) and the ephorate (through a mysterious «third savior » ). So, between Plato’s views and Xenophon’s (the first to conceptualize Spartan constitution), what is at first sight obvious is their opposition ; but both authors also share important ideas : they take kingship to be the central institution, and they see in the limitations to its power (symbolized by the oaths mutually...